Maricopa County Planning and Development: Unincorporated Area Governance
Maricopa County Planning and Development (MCPD) exercises land use and building authority over unincorporated territory — the roughly 9,000 square miles of Maricopa County that lie outside the boundaries of any incorporated city or town. This page explains how that authority is defined, how permit and zoning decisions are processed, the property scenarios most commonly encountered, and where the decision-making boundary falls between the county and neighboring municipalities. Residents, landowners, and developers operating in unincorporated areas face a regulatory framework that is distinct from any city's code, making an accurate understanding of jurisdictional scope essential before submitting any application.
Definition and scope
Maricopa County is Arizona's most populous county, home to more than 4.4 million residents (U.S. Census Bureau, 2020 Decennial Census), distributed across 27 incorporated municipalities and a substantial band of unincorporated land. MCPD governs land use, zoning, subdivision platting, building permits, grading, and floodplain management exclusively within that unincorporated territory. The department operates under authority granted by the Arizona Revised Statutes Title 11, which assigns counties the power to regulate land use and development outside incorporated municipal limits.
Scope and coverage: MCPD's jurisdiction applies to properties whose legal addresses fall outside incorporated city or town limits, even when those properties are physically adjacent to a city. The department's authority does not apply to parcels within the corporate limits of Phoenix, Mesa, Scottsdale, Chandler, Tempe, Gilbert, Glendale, Peoria, or any other incorporated municipality in the county. Properties within those cities are governed by each city's own planning and development department — for example, land within Phoenix's city limits falls under Phoenix Planning and Development.
Not covered by MCPD: state trust land administered by the Arizona State Land Department, tribal lands governed under federal tribal sovereignty, and federal land managed by the Bureau of Land Management or U.S. Forest Service.
How it works
MCPD administers a parallel regulatory structure to what incorporated cities operate, but under county-specific codes. The primary instruments are:
- Maricopa County Zoning Ordinance — establishes base zone districts (residential, commercial, industrial, agricultural) and the permitted, conditional, and prohibited uses within each district across unincorporated land.
- Maricopa County Subdivision Regulations — govern the division of land into parcels, requiring plat review and approval before lots can be legally sold or built upon.
- Maricopa County Building Codes — adopt and amend the International Building Code (IBC) and International Residential Code (IRC) for construction permits, inspections, and certificates of occupancy.
- Flood Control District coordination — projects near washes or within FEMA-designated Special Flood Hazard Areas require concurrent review by the Maricopa County Flood Control District (MCFCD).
Applications are submitted to Maricopa County Planning and Development and reviewed by departmental staff. Zoning variances, use permits, and rezoning requests require a hearing before the Maricopa County Board of Adjustment or the Maricopa County Board of Supervisors, depending on the nature of the request. Building permit applications for straightforward construction can be processed administratively without a public hearing.
Processing timelines vary by application type. Standard residential building permits in unincorporated areas are typically reviewed within 10 to 15 business days under the department's published service standards (MCPD Service Standards, maricopa.gov). Rezoning cases that proceed to the Board of Supervisors are calendared on a monthly hearing cycle.
Common scenarios
The following situations most frequently require engagement with MCPD rather than a city planning department:
- Rural residential construction — A landowner building a single-family home on a parcel outside any city limit must obtain a county building permit, comply with county setback and lot coverage rules, and pass county inspections.
- Agricultural operations with structures — Barns, equipment storage buildings, and accessory dwelling units on agricultural-zoned parcels in the far West Valley or southeast county require county review even when no city is nearby.
- Short-term rental registration — Arizona state law (A.R.S. § 9-500.39) affects short-term rental regulation, but for unincorporated parcels the county's own regulations — not a city's STR ordinance — control noise, parking, and occupancy standards.
- Subdivision of land — A property owner dividing an unincorporated parcel into 2 or more lots triggers the county's subdivision platting process, including infrastructure improvement requirements.
- Commercial development on highway corridors — Strip commercial development along unincorporated stretches of arterials such as Gila Bend Highway or Carefree Highway is reviewed by MCPD, not by adjacent city departments.
Decision boundaries
The most consequential boundary question is whether a given parcel is inside or outside an incorporated municipality. That determination is not always visually obvious — county "islands" (unincorporated parcels surrounded by city territory) exist in Maricopa County, and their governance differs from neighboring incorporated land.
County vs. city jurisdiction — key distinctions:
| Factor | MCPD (Unincorporated) | Incorporated City |
|---|---|---|
| Zoning authority | Maricopa County Zoning Ordinance | City-specific zoning code |
| Building permit issuer | Maricopa County | City building department |
| Appeals body | County Board of Adjustment | City Board of Adjustment or equivalent |
| Police jurisdiction | Maricopa County Sheriff's Office | City police department |
Annexation changes the picture entirely. When an incorporated city annexes unincorporated land under A.R.S. § 9-471, the property transitions from county to city jurisdiction. Active building permits issued by the county before annexation typically remain valid through completion, but all subsequent applications fall under the city's regulatory authority.
For properties in the process of annexation, or near contested municipal boundary lines, confirming the current jurisdictional status through the Maricopa County Assessor parcel viewer is the standard verification method before filing any application. A broader orientation to county-level governance across all departments is available on the Phoenix Metro Authority index.
References
- Maricopa County Planning and Development Department
- Maricopa County Board of Supervisors
- Arizona Revised Statutes Title 11 — Counties
- Arizona Revised Statutes § 9-471 — Annexation
- Arizona Revised Statutes § 9-500.39 — Short-Term Rentals
- Maricopa County Flood Control District
- Maricopa County Assessor
- U.S. Census Bureau — 2020 Decennial Census, Maricopa County
- International Building Code (IBC) — International Code Council